Polyhalide particles and light valves comprising same

Abstract

A polyhalide light-polarizing material comprising a complex obtained by reacting: (a) elemental iodine; (b) a hydrohalide acid or an ammonium halide, alkali metal halide or alkaline earth metal halide; (c) a first compound capable of chelating hydrogen, ammonium or metal ions; and (d) a second compound comprising at least one chelating group present in the first compound and either (1) at least one group of the first compound is changed to a different group or (2) the second compound comprises at least one additional group.

What is claimed is:  
     
       1. A polyhalide light polarizing material comprising a complex obtained by reacting: (a) elemental iodine; (b) a hydrohalide acid or an ammonium halide, alkali metal halide or alkaline earth metal halide; (c) a first compound comprising a pyrazine-2,5-dicarboxylic acid; and (d) a second compound comprising a mono-alkyl ester or a mono-amide of a pyrazine-2,5-dicarboxylic acid. 
     
     
       2. The light polarizing material of  claim 1 , wherein the first compound is a dihydrate of the dicarboxylic acid and the second compound is a monohydrate of the dicarboxylic acid. 
     
     
       3. The light polarizing material of  claim 1 , wherein the mono-alkyl ester is a mono C 1 -C 20  alkyl ester and the nitrogen of the monoamide is optionally substituted by one or more alkyl groups. 
     
     
       4. A method of making a polyhalide light-polarizing material comprising forming a complex by reacting: 
       (a) elemental iodine; (b) a hydrohalide acid or an ammonium halide, alkali metal halide or alkaline earth metal halide; (c) a first compound capable of chelating hydrogen, ammonium or metal ions; and (d) a second compound comprising a mono-alkyl ester or a mono-amide of a pyrazine-2,5-dicarboxylic acid.  
     
     
       5. The method of  claim 4  wherein the first compound is a dihydrate of a pyrazine-2,5-dicarboxylic acid and the second compound is a monohydrate of the pyrazine-2,5-dicarboxylic acid. 
     
     
       6. The method of  claim 4  wherein the mono-alkyl ester is a mono C 1 -C 20  alkyl ester and the nitrogen of the mono-amide is optionally substituted by one or more alkyl groups. 
     
     
       7. The polyhalide light-polarizing material of  claim 3  wherein the nitrogen of the monoamide is substituted by one or more C 1 -C 10  alkyl groups. 
     
     
       8. The polyhalide light polarizing material of  claim 1  wherein the amount of the second compound ranges from about 0.01 mol % to about 10 mol % of the first compound. 
     
     
       9. In a light valve, comprising a cell containing a suspension of light-polarizing particles in a liquid suspending medium, the improvement wherein the light polarizing particles are comprised of the light polarizing material of  claim 1 . 
     
     
       10. The method of  claim 4 , wherein the first compound is a pyrazine-2,5-dicarboxylic acid. 
     
     
       11. The method of  claim 6  wherein the nitrogen of the monoamide is substituted by one or more C 1 -C 10  alkyl groups. 
     
     
       12. The method of  claim 4 , wherein the amount of the second compound ranges from about 0.01 mol % to about 10 mol % of the first compound.